Ladder



April E. J. ARPS LADDER Filed Feb. 8, 1937 FIG. I. FIG. 2. :1) W

9--- ix INVENTOR EDMUND J. ARPS x ATTORNEYS UNITED STATES PATENT OFFICELADDER Edmund J. Arps, Oshkosh, Wis., assignor to Duo- Safety LadderCorporation, Oshkosh, Wis.

Application February 8, 1937, Serial No. 124,701

1 Claim.

My invention refers to ladders, and it has for its primary object toprovide a non-conducting ladder for various purposes, comprising acombination of wooden and metallic elements, where- 5 by the ladder isnot only insulated but is rendered by its structure strong, light, anddurable. The ladder is especially designed for fire purposes, andembodies a plurality of telescopic elements for extension to variousheights.

l I am aware of the fact that wooden ladders of this extension type havebeen heretofore manufactured, and, also, all-metal ladders, but in eachinstance the weight is detrimental to functioning, and the woodenladders or ladder sections are 15 frequently weakened by coming incontact with fire hazards. The metal ladders have been found in practiceto be heavy, and toact as ground conductors for any live wire contactthat may develop in fighting fires..

20 With the above and other minor objects in view, the inventionconsists in certain peculiarities of construction and combination ofparts, as will be hereinafter set forth in the drawing, and subsequentlyclaimed.

25 In the drawing:

Figure 1 represents a sideelevation of a combination wood and metalladder embodying the features of my invention.

2 is. a face. view, with parts broken away 30 and in section, to moreclearly illustrate structural features.

Figure 3 is an enlarged, fragmentary, detail, side elevational view of ametallic bracket element associated with wood rails, parts being 35broken away to more clearly illustrate structural features.

Figure 4 is a cross section of the same, the section being indicated byline 4-4 of Figure 1.

Figure 5 is a similar cross section of the ladder 40 element,illustrating a preferred form of bracket associated with the wood rails.

Referring by characters to the drawing, l-l' represent wood stripsspaced apart to form skeleton side rails of the ladder. The upper andlower 45 ends of the ladder section are provided with filler blocks 2and 3, respectively, which filler blocks are composed of wood in thisinstance, although in some cases they may be all-metal. The wood fillerblocks are snugly fitted between the ends of 50 the strips l-l, and areglued thereto. The assemblage is further secured by bolts or rivets 4-4and 5-5, which pass through the wood rail strips, filler, and preferablyreinforcing metal bands 6-6. The upper metal band is bowed 55 around theend of the ladder, and is secured by the bolt 4, while the lower bands6', in this particular instance, are simply shown to reinforce theelements secured by the bolts5, and the filler of this bottom. endsection may be routed out, as indicated at X, whereby the prongs areformed 5 to prevent the last or bottom section from slipping.

It is understood, while I have shown only the bottom section, asindicated in dotted lines, Fig ures 3 and 4, a plurality of thesesections may be 10 telescopically mounted one upon the other, wherebythe proper height is obtained through extension of these Varioussections, which arrangement is common in the art. The filler blocksZ and3 each have a tubular rung l, which is rectangular in cross section, theends being embedded in apertures formed in the blocks 2 and 3, said endsbeing further secured by bolts 5 passing therethrough. Another tubulartread rung 8 is provided for the blocks in this particular instance, butit is understood that one, or a series of said tread rungs, maybeemployed. The ends of this tubular tread rung are initially fittedthrough apertured metallic plates 9, and the ends of the tubular rungare provided with pairs of expansions orbeads Ill-l0 upon opposite sidesof the, plate, whereby these parts are permanently secured. Thereafterthe ends of the tubular rung are fitted into apertures which are boredinto the blocks, and the plates 9-9 are secured to said blocks bysuitable screws, it being understood that the plates are fitted into theinner faces of the blocks.

In the event that the wood filler blocks should be formed from hollowmetal elements, means for securing the rungs thereto would be similar tothe means employed in connection with a plurality of metal brackets ll.As best shown in Figures 3 and 4 of the drawing, the metal brackets Hare formed from a pair of plates l2-I2', which plates are spaced apartand provided with alined apertures for reception of the ends 1/ ofmetallic tubular rungs l3.

After the end of each rung is fitted through the plate apertures, it iscrimped or beaded at the points l4 and M, to form shoulders between theinner and outer faces of the wall l2, whereby endwise movement of therung is eliminated. The extreme end of the rung or tube l3, as bestshown in Figure 4, is then crimped or beaded at the point IE, to form ashoulder which impinges against the inner face of the wall 12, and theopening in said wall is slightly depressed about the end surface of thetube, whereby said end surface is soldered or welded to the outersurface 56 of the bracket plate I2, to thus insure a permanentconnection which is smooth in finish, and at the same time connects theparts, forming in effect a homogeneous mass.

The plate elements I2 and I2 are each inwardly formed with flanges IIi-I 6, which flanges are in sliding fit, and have nested thereagainstthe wood rail strips II it being understood that the flanges are thensecured to the wood rails by bolts or screws II. Thus, the brackets notonly form metallic supports for the tubular rungs, but they also act asbraces for the skeleton rail structure, whereby each ladder section willresult in a strong and durable assemblage. Owing to the fact that therail elements are composed of wood, and the transversely disposed rungand supporting brackets are of metal, preferably aluminum, the structureis interrupted, or insulated, whereby stray currents of electricity willnot be grounded through the ladder sections, due to this insulation,which is a vital and important feature accomplished by my compositestructure. From the foregoing description of the plate elements andladder rungs, it should be understood that prior to assemblage of thehollow bracket embodying the spaced plates I2I2 the rung is first fittedin the aperture of the inner plate and beaded upon opposite sides tolock it. Thereafter, just back of the end of the rung I3 the same isbeaded to form a shoulder I5. The next operation for assemblage is thatthe plate I2 is slit over the end of the round, and secured thereto bywelding, or analogous means. Hence, it will be observed that I providean integral all-metallic fitting, a series of which can be thereafterreadily inserted along the length of the ladder, whereby the skeleton orspaced strips Will be secured to the bracket elements by bolts, to thussecurely stiffen the ladder as a whole, bracing the spaced wood elementsin a vertical direction, and also transversely, due to the rungs I3which constitute tie rods.

In Figure 4 of the drawing, the inner plate or wall of the bracketelement is illustrated as having a depression I8, which serves as astirrup or guide shoe for the rail strip I, which rail strip isindicated by dotted lines as fitting into the depression of the shoe.However, as shown in Figure 5 of the drawing, this depression may bedispensed with, and the rail strips and bracket surfaces in themselveswill form the shoes or interlocking elements.

In the above referred to modified construction, the surface of the plateI 2 forms a sliding shoe for the rail element, indicated in dotted linesof Figure 4. For example, this rail element will abut the projection ofthe strip I with the bottom surface of said rail element riding upon theplate. Briefly, the projecting surface of the rail element I serves toprevent side play of the sliding ladder section, thus dispensing withthe depression I8.

While I have shown and described the brackets as being composed of twometallic strips bolted and secured together, it is obvious that thishollow bracket element may be formed from a single strip folded uponitself without departing from the spirit of my invention. Furthermore,it is understood that in manufacturing intermediate ladder stretches forthe extension assemblage, the lower ends of such intermediate sectionswill be provided with finishing blocks 2 and 3, but the forked orspurred end in such instances will be eliminated. Furthermore, inmanufacture the spurred or lower end of the bottom ladder section can beindefinitely varied in structural features, it being simply necessary toprovide any type of spur element to prevent the ground or initial laddersection from slipping when these ladder sections are used independentlyof a truck.

While I have shown and described one example of my invention minutely asto all details, it is understood that I may vary the structural featureswithin the scope of the claim.

I claim:

In a ladder, rails of skeleton-like form including longitudinallyextending spaced strips, and an all-metal fitting disposed between thestrips, said fitting comprising a pair of inner and outer spaced plateshaving alined openings, rightangular interengaging flanges extendingfrom the plates for connection with the strips, tubular rungs havingends fitted through the alined openings of the plates, beads formed onthe rung on opposite sides of the inner plate forming shoulders againstthe inner and outer surfaces of the inner plate, means securing the endof the rung to the outer plate, whereby the plates and the rung form asingle unit, and means for securing the flanges of the plates to thestrips.

EDMUND J. ARPS.

